1. Field of the Invention
The present invention relates to an image surveillance apparatus having an imaging device installed so as to observe a certain surveillance region, wherein an image obtained by this imaging device is processed in order to detect a person or object which intrudes into the surveillance region. The present invention further relates to an image surveillance method and an image surveillance processing program implemented in such an image surveillance apparatus.
2. Description of the Related Art
In recent years, an imaging device such as an industrial television camera (hereinafter “ITV camera”), or the like, has been used in surveillance apparatuses. These kind of surveillance apparatuses are installed at an appropriate place in a factory building. The surveillance apparatus monitors an image obtained by an imaging device of the surveillance apparatus. Such a surveillance apparatus has been effectively used for improving security of a factory building by detecting occurrence of an abnormal event and intrusion of criminals into the factory building.
As for a surveillance apparatus used for such an application, an image of a certain region to be monitored is obtained by an ITV camera installed on a ceiling, or the like, and the image obtained by the ITV camera is used as a surveillance image for surveilling the surveillance region. The surveillance apparatus compares the surveillance image of the surveillance region, which is captured by the ITV camera and updated every predetermined time (hereinafter, referred to as “current image”), with a surveillance reference image, which is a background constantly present in the surveillance region and which is previously stored in the surveillance apparatus (hereinafter, referred to as “background image”). If the current image differs from the background image, the surveillance apparatus determines that there is an intruder, or the like, in the surveillance region.
When the surveillance apparatus detects intrusion of an intruder as a result of the comparison between the current image and the background image, for example, the surveillance apparatus informs a surveillant or operator who is monitoring the surveillance region through the surveillance apparatus that an intruder is detected. The surveillant informed of that intrusion goes to the place in the surveillance region where intrusion was detected, or takes any necessary action.
However, in a conventional image surveillance apparatus, the angle of view of an imaging device is narrow, such that the surveillance region that is covered by a single imaging device is limited. Thus, when it is necessary to surveil a large surveillance region, a plurality of imaging devices have to be installed at appropriate positions so that the entire surveillance region can be covered by the imaging devices. Alternatively, an imaging device has to be movable so that a large surveillance region can be covered by the single imaging device.